Drive control for self-propelled power tool

ABSTRACT

A large capacity, self-propelled walk-behind power tool, such as a lawn mower, employs gear-operated transmissions for independently driving each drive wheel. Control handles are connected to idler pulley levers and brake levers to control the movement of the driving wheels. A constant input rate to the control handles results in a variable output rate to the idler pulley levers and the brake levers.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to self-propelled, walk-behind powertools, such as lawn mowers, snow blowers or power sweepers, or likeequipment. More particularly, the invention involves an effective, yetless expensive, drive system which is able to independently operate eachdrive wheel of the power deck of such tools in a manner to effectaccurate and safe operation thereof.

2. Description of the Related Art

Although the present invention has utility in walk-behind snow blowers,power sweepers, or the like, the most common utilization of theinvention is anticipated for lawn mowing equipment of the concernedtype, and particularly, in large capacity, commercial walk-behindmowers. Consequently, except where otherwise expressly stated, thedescription herein is directed to walk-behind lawn mowing equipment,particularly large capacity lawn mowers.

Large capacity commercial-type self-propelled walk-behind lawn mowerscommonly have a power deck containing two driven wheels and handle barsmounting the operating handles for the various mower control elements.The mower or tool deck, which connects with the power deck, carriesidler or caster wheels to support and balance the mower deck.

Desirably, power input to the drive wheels is effected separately andindependently to the respective drive wheels. This allows the machine tobe effectively steered by varying the driving input and the braking ofone wheel with respect to the other whereby the machine is able to turnabout a tight radius.

Most commercial lawn mowers of the prior art employ drive wheels andmower blades which are belt-driven by a motor through transmissionsystems which utilize output-varying devices for regulating theoperation of the various tools and wheel drives. The transmissionsystems may be hydrostatic transmissions which comprise at least onepump connected to the engine output, typically by a belt and pulleysystem. The pump or pumps are operable to drive hydraulic motors thatare drivingly connected to the respective mower drive wheels and thatare independently controlled by means of operating controls mounted onthe mower handle bars. Hydrostatic transmissions, although relativelyhigh in cost, have the advantage that the speed and direction of eachwheel can be infinitely varied between a lower limit and an upper limitwith fewer moving parts than are contained in a conventionalgear-operated transmission.

Hydrostatic transmissions have the further advantage that the drivewheels of the power deck can be directly coupled to the hydraulic motorconnected to the hydrostatic transmission and, as with hydrostatictransmissions arranged in a lawn mower as shown and described in U.S.Pat. No. 5,127,215 to P. H. Wenzel, the transmission input shaft and theengine drive shaft can rotate about parallel axes whereby the amount ofspace occupied by the drive train is reduced to an extent that all ofthe operating parts can be conveniently enclosed by a deck bed whichforms a protective covering over the drive train components for safetypurposes and to protect the components from damage.

The other, less expensive, form of transmission employed with commerciallawn mowers is a multi-speed geared transmission which obtains inputfrom an engine via a belt and pulley system and outputs, throughappropriate gearing, a plurality of discrete speeds to the drive wheelsof the power deck. In this form of transmission system, the output fromthe transmission is typically transmitted to each drive wheel byseparate belt and pulley systems. Torque transmitted to the respectivewheels is, as shown for example, in U.S. Pat. No. 4,558,558 to H. F.Horner Jr. et al. and U.S. Pat. No. 5,343,678 to T. G. Stuart,controlled by a clutch device in the form of an idler pulley mounted onan arm that pivots into increasing or decreasing engagement with thewheel drive belt so as to vary the tension on the belt and thus the wrapangle about the respective driving and driven pulleys to selectivelyadjust the torque being transmitted therebetween.

Gear-operated transmissions for self-propelled, commercial-type lawnmowers suffer the disadvantage that the amount of torque transferred tothe drive wheels is proportional to the wrap angle of the belt aroundthe drive and driven pulleys. The belt must be tensioned in order toincrease these wrap angles. Therefore, the operator must apply a largeforce to the idler. However, this input by the operator is stronglyresisted by the belt. This resistance can fatigue the operator's hands.

It is to the amelioration of such problems in self-propelled,walk-behind power tools, such as lawn mowers, to which the presentinvention is directed.

SUMMARY OF THE INVENTION

The present invention provides a lawn mower drive system in which geartransmissions are employed in such manner as to produce many of theadvantages heretofore obtained only from hydrostatic transmissions andwithout the cost attendant with the use of hydrostatic transmissions.The components of the instant lawn mower drive system are so arrangedthat the control input by the operator is translated into a variableoutput to the drive belts and brakes. The amount of effort required toadjust the driving force in the most frequently used range of operationof the controls is reduced. Therefore, operator fatigue is reduced.

Accordingly, the present invention provides a self-propelled,walk-behind power tool comprising a power deck including a bed, anengine mounted on an upper surface of said bed and having a rotatabledrive shaft depending therethrough, left and right drive wheels eachbeing journalled on opposite sides of the bed for rotation about anaxle, and means for connecting the engine to the drive wheels includinga pair of idler pulley levers pivotally attached to the bed, a handlebar attached to a rear side of said power deck, left and right controlhandles positioned on the handle bar, means for biasing the controlhandles to a neutral position, the control handles being pivotable fromthe neutral position to a drive position, and first means for moving oneof the idler pulley levers at a first rate in response to a constantinput to pivot one of the control handles from the neutral position to afirst position intermediate the neutral and drive positions and at asecond rate in response to the constant input to pivot the one controlhandle from the intermediate position to the forward position.

The present invention may additionally include a pair of brake leverspivotally attached to the bed, the biasing means also biasing thecontrol handles from the a brake position opposite the drive position tothe neutral position, and second means for moving one of the brakelevers at a first rate in response to a constant input to pivot thecontrol handle from said neutral position to a second positionintermediate the neutral and brake positions and at a second rate inresponse to the constant input to pivot the control handle from thesecond position to the brake position.

It is accordingly a particular object of the present invention toprovide a lawn mower drive system which permits use of a less expensivegear-operated transmission for the drive wheels but is nonetheless ableto manifest several advantageous features which heretofore have beenunique to drive wheels that are driven by hydrostatic transmissions.

It is a further object of the present invention to provide a lawn mowerbelt drive system wherein a particular relationship is establishedbetween the elements of the system which reduces operator fatigue.

For a better understanding of the invention, its operating advantagesand the specific objectives obtained by its use, reference should bemade to the accompanying drawings and description which relate to apreferred embodiment thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a self-propelled, walk-behind form oflawn mower incorporating the present invention;

FIG. 2 is a side elevational view, partly in section, of the lawn mowerillustrated in FIG. 1;

FIG. 3 is a partial side elevational view of the handle bar andcontrol-operating handles mounted thereon employed on the mower of FIG.1;

FIG. 4 is a partial perspective view illustrating in greater detail thecontrol elements and the drive pulley arrangement shown in FIG. 3;

FIG. 5 is another partial perspective view of the control elements andother elements controlled thereby as shown in FIG. 3;

FIG. 6 is. a view taken along line 6--6 of FIG. 3;

FIG. 7 is a plan view of the belt and pulley system employed foroperating the drive wheels of the present invention;

FIG. 8 is a partial perspective view of the power deck with drive leversand parking brake operator mounted thereon;

FIG. 9 is a rear view of the power deck and drive levers of FIG. 8;

FIG. 10 is a partial elevational view with portions removed taken alongline 10--10 of FIG. 7;

FIG. 11 is a perspective view of the parking brake operator elements ofthe present invention;

FIG. 12 is a schematic view illustrating parking brake operator elementsin various positions;

FIG. 13 is a partial perspective view of the operating handle andpresence lever for forward operation of the drive wheel on the rightside of the lawn mower shown in FIG. 1;

FIG. 14 is a view similar to FIG. 12 showing the operating handle andpresence lever for reverse operation of the drive wheel on the rightside of the lawn mower shown in FIG. 1;

FIG. 15 is a schematic representation of the control circuitry for thelawn mower of the present invention;

FIG. 16 is a partial perspective view of the blade brake and operatingelements thereof for the lawn mower of the present invention;

FIG. 17 is a more detailed partial perspective view of the blade brakeand operating elements thereof shown in FIG. 15;

FIG. 18 is schematic representation of the control elements of thepresent invention; and

FIG. 19 is a chart illustrating the movement rates for the controlelements of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Although the present invention has application to power tools of variousforms, such as snow blowers, power sweepers, or the like, the drawingfigures illustrate an embodiment of the invention in which the operationelement of the power tool is a lawn mower, particularly one employingmultiple rotary blades as is common in large capacity, commercial formsof lawn mowing equipment. Also, although the disclosed lawn mower isdescribed as being a "walk-behind" lawn mower, the concerned inventionis equally applicable to power equipment attaching a "sulky" or aplatform on which the operator may ride.

The described lawn mower 10, as best shown in FIG. 2, contains a powerdeck 12 and a tool-or mowing-deck 14. Desirably, the mowing deck 14 isdetachably connected to the power deck 12 to permit substituting for themowing deck, either a snow blowing apparatus or a power sweepingapparatus, neither of which is shown herein.

The power deck 12 contains a bed 16 defined by a generally rectangularsheet metal plate 18 having downturned flanges 20, 22 and 24 withflanges 20 and 22 being disposed along the laterally spaced sides of thebed, and flange 24 extending between, and interconnecting, the sideflanges at the rear of the bed. An engine 26 is mounted on the uppersurface of the bed 16 wherein a through-opening 28 is provided toaccommodate passage of the engine drive shaft 30 to the underside of thebed plate 18. An inverted U-shaped bracket 32 has its down-turned legs32a and 32b secured to the rear end of the bed 16 and its upwardlydisposed platform portion mounting a fuel tank 34.

A pair of laterally spaced drive wheels, including left wheel 36 andright wheel 38, are disposed on opposite sides of the bed 16 in a mannerhereinafter more fully described. Also, a pair of laterally spacedsupport arms 40 extend longitudinally forward from the bed 16 forattaching the mowing deck 14. The support arms 40 are fixedly secured attheir respective rear ends to the bed and at their forward ends eachmount left and right caster wheels 42 and 44, respectively, which arejournalled for free rotation about a vertical axis by associated supportshaft housings 460. As shown best in FIG. 2, the mowing deck 14 ismounted via laterally spaced brackets 448 carrying pivot pins 450 whichpivotally engage the respective support arms 40 adjacent the forwardends thereof. A height adjusting mechanism 452 secures the rear end ofthe mowing deck 14 in a manner which permits height adjustment of themowing deck.

As shown in FIGS. 3, 4 and 5, a handle bar 56 having a pair of left andright depending arms 58 and 60, respectively, is fixedly secured to thedownturned legs of the bracket 32. A panel plate 62, that issubstantially coextensive with the space along the handle bar 56 betweenthe arms 58 and 60 provides access to control elements, as hereinafterare more fully described.

Drive Controls

With particular reference to FIGS. 2 to 10 of the drawings, lawn mowercontrol apparatus is shown for controllably operating the left and rightdrive wheels 36 and 38. The control apparatus includes individual leftand right gear-operated transmissions 64 and 66, respectively. Thetransmissions are mutually spaced laterally with respect to each otherand each has a horizontally extending output shaft (not shown) extendingin opposite directions away from each other with each output shaft beingadapted to mount a hub of one of the drive wheels 36, 38. Thetransmissions are structurally interconnected on their respective facingends by means of appropriate connecting structure (not shown) and arefixedly secured to the bed 16 of the power deck 12 by means ofconnectors (not shown) that attach posts which surround an output shaftbearing bushing 72 to laterally extending support ears 74 fixedlysecured to the respective side flanges 20 and 22 of the power deck bed16. Power input to each transmission 64, 66 is effected by a belt-driveninput pulley, indicated as 76 on the left transmission 64 and as 78 onthe right transmission 66. Each pulley 76 and 78 is fixed to androtatably drives input shafts on the respective transmissions 64, 68 andextends substantially parallel to the engine drive shaft 30.

As indicated in FIGS. 3, 4, 6 and 7 of the drawings, the engine driveshaft 30, which rotates about a vertical axis, mounts a pair ofvertically spaced pulleys 80, 82, about the respective ones of which thedrive belts 84, 86 extend. Drive belt 84 extends between the uppermostpulley 80 on the engine drive shaft 30 and the pulley 76 on the inputshaft to the left transmission 64. Drive belt 86 extends between thenext lower pulley 82 on the engine drive shaft 30 and the pulley 78 onthe input shaft to the right transmission 66. As shown, the input pulley76 on the left transmission 64 is disposed slightly higher than pulley78 on the right transmission and substantially level with the pulley 80on the engine drive shaft 30. Similarly, the input pulley 78 on theright transmission 66 is disposed substantially level with the pulley 82on the engine drive shaft whereby the drive belts 84 and 86 each operatein substantially level, horizontal planes.

A third pulley, termed "the power take-off (PTO) pulley," 88 is disposedat the lower end of the engine drive shaft 30 and is engaged by a drivebelt 90 employed to rotatably drive the mower blades, as describedhereinafter.

Belt guards, in the form of rod members 91 attached at one of their endsto the bed 16, have offset portions positioned closely adjacent thevarious belts and serve to prevent the respective belts from becomingdislodged from the pulleys which they engage.

Power input to the respective drive wheel transmissions is individuallycontrollable by means of clutch elements 92, 94 which are each in theform of idler pulleys 96, 98 that rotate on one end of pivotable leverarms 100, 102, respectively, whose opposite ends are pivotally securedto the undersurface of the metal bed plate 18. As shown best in FIGS. 6and 7, the lever arms 100, 102 which carry the respective idler pulleys96, 98 are each disposed within the space surrounded by the drive beltwith which each is associated. Return springs 129 which have one endconnected to the bed 16 and the other end connecting each lever arm 100,102 serve to normally bias the idler pulleys 96, 98 away from theirrespective drive belts 84, 86. Also, appropriate limit stops (not shown)extend from the bed plate 18 and serve to limit the angulardisplacements of the lever arms 100, 102 when they are pulled intodisengagement by the return springs 129.

Each of the wheel drive transmissions 64 and 66 is a multi-speed gearedtransmission which produces discrete selected speeds that the panelplate 62 indicates by notches 104 as best shown in FIG. 4, and includefour forward speeds, a reverse speed and a neutral position. A tandemcontrolled transmission shifting device 105 (FIG. 7) is operative tochange the gear of the respective transmissions 64, 66. Gearedtransmissions, suitable for use in the practice of the invention, arethose made by Dana Corp. under Model No. 4360-102.

Separate control members operate the clutch elements in order to varytorque transmission between the output of the engine drive shaft 30 andthe input to the respective left and right drive transmissions 64, 66.Thus, as shown in the drawings, the bracket 32 on the power deck 12mounts a support shaft 106 which extends between, and is fixed at itsends, to the respective legs 32a and 32b of the bracket. Drive levers108 and 110 having the general shape of an inverted J and disposed ataxially spaced locations along the shaft 106 contain clearance openingsin the legs of the levers which enable the levers to undergo controlledpivoted movement about the shaft. Spacers 112 serve to separate thedrive levers 108, 110 from the respective legs 32a, 32b of the bracket32. Each drive lever 108, 110 has an upper portion 108a, 110a and lowerportion 180b, 110b.

Each of the drive levers 108, 110 is independently operated by arespective one of a pair of control handles 114, 116 which are disposedfor pivotal movement on the handle bar 56 and that contain transverselyextending upper portions to facilitate manual manipulation by themachine operator. An arm 115 is rigidly fixed to each control handle 114and 116. The arms 115 pivot with the control handles 114, 116 about thepivot 117. Each connecting rod 118 is pivotally attached to one of thearms 115 by a pivot 119 and to upper portion 108a, 110aof one of thedrive levers 108, 110 by a pivot 133. Axial adjustment of the respectiveconnecting rods with respect to their associated drive lever can beeffected by a turnbuckle 120 which connects an upper portion 118a to alower portion 118b of each connecting rod. The control handles 114 and116 are biased from the drive position to a neutral position by thereturn springs 129.

The lower portion 108b, 110b of each drive lever 108, 110 pivotallyattaches at hole 108c to a drive spring 122 which extends forwardly fromthe drive lever and is generally axially stiff. The springs 122 have atone end a hook 124 that pivotally engages an opening 126 in thedepending leg of the drive lever 108 and 110. The other end of eachspring 122 contains an elongated loop 125 forming a lost motion spaceand that, with regard to the left idler pulley 96, engages a pin 127which depends from the underside of the lever arm 100. With regard tothe right idler pulley 98, and in order to accommodate the unequalvertical spacing between the drive belts 84 and 86, the looped end 125of the associated spring 122 engages the lower end of bent pin 128 whoseupper end is fixed, as by means of welding, or the like, to the edge ofthe right idler pulley lever arm 102.

Thus, operation of the mower in the forward direction involves, first,the transmissions 64 and 66 associated with the respective wheels 36 and38 being placed by the operator in a selected drive range, as determinedby placement of the shift lever 130 in an appropriate notch 104 in thepanel plate 62. To propel the mower straight forwardly both uppercontrol handles 114a and 116a are simultaneously moved forwardlywhereupon the drive levers 108 and 110 are pivoted about the supportshaft 106 in a direction to extend the drive springs 122 rearwardlywhich causes the lever arms 100 and 102 carrying the idler pulleys 96and 99 to be controllably urged into engagement with the respectivedrive belts 84 and 86 thereby adjusting the tension of the respectivedrive belts about the pulleys they engage. Such adjustment alters thetorque transmission from the engine drive shaft 30 to the left and righttransmissions 64 and 66, respectively, within the selected gear range.To steer the mower 10, the operator need only push or pull one controlhandle with respect to the other whereupon the driving force to onedrive wheel with respect to the other is altered thereby causing thecourse of the machine to be altered.

Reverse propulsion of the mower 10 is accomplished by first moving theshift lever 130 to the reverse position in the notches 104. Then, thelower control levers 114b and 116b of the control handles 114 and 116are pulled rearwardly. This rearward motion of the lower control handles114b and 116b has the same effect as the forward motion of the uppercontrol handles 114a and 116a. The mower 10 may be steered in reverse inthe same manner as the forward driving.

Braking of the respective drive wheels 36 and 38 in order to stopforward movement of the machine, or to augment its turning movements, iseffected by the operator pivotally moving one or the other or both ofthe control handles 114 and 116 in a direction opposite to that requiredfor effecting rotation of the drive wheels 36, 38 for forward movement.Thus, to brake the left drive wheel 36, for example, the control handle114 which controls operation of the left drive wheel is pivoted, eitherby pulling its upper control handle 114a backwardly or by pushing itslower control handle 114b forwardly. By imparting such movement to thecontrol handle 114, the connecting rod 118 which interconnects the leftcontrol handle 114 with the left drive lever 108 causes the drive lever108 to rotate in a clockwise direction, as viewed in FIG. 10, whereuponthe left brake lever 134 which connects to the drive lever 108 viaconnecting link 135 is pivoted in a clockwise direction about pivot pin136 to cause brake band 138 whose ends connect with the brake lever viapin connectors 140 to constrict the brake pad 142 about the brake drum144 on the wheel. Note that the brake drum 144 for the left wheel 36 hasbeen omitted for clarity and that FIG. 10 shows only the brake drum 144that is connected to the right wheel 38. The brake bands 138 bias thecontrol handles from the brake position to the neutral position.

The connecting link 135 includes an elongated loop 135a that forms alost motion coupling with the drive levers 108 and 110. This loop 135aallows the drive levers 108 and 110 to rotate counterclockwise (asviewed in FIG. 10) to engage the idler pulleys 96 and 98 with theirrespective drive belts 84 and 86 without imparting further motion ontothe brake levers 134 which would cause further separation of the brakebands 138 from the brake drums 144.

The simultaneous braking of both drive wheels 36 and 38 is effected byperforming the above-described operation simultaneously on both controlhandles 114 and 116. Alternatively, in order to augment turning of themachine, one of the drive wheels can be substantially fully or onlypartially braked while the other drive wheel continues to be drivenforwardly so as to effect a tight turn.

It will be appreciated that the power tool drive apparatus describedherein, utilizing gear-operated drive transmissions, produces operatingcharacteristics and features which heretofore were unique to equipmentemploying hydrostatic transmissions for transmitting engine power to thedrive wheels. The disclosed arrangement provides a compactness of formwhich enables all of the components, which define the drive train, to beenclosed by the power deck bed, thus to protect the drive traincomponents against damage occurring from the components contacting treelimbs or other vegetation, or the like. Conversely, by enclosing thedrive train components, the machine operator and others who might comein close proximity to the machine are protected against injury caused bycontact with moving drive train components.

These and other advantages previously attributable to hydrostatictransmissions are effectively obtained from gear-operated transmissionsby practice of the invention wherein the clutching function, which isrequired for the use of gear-operated transmissions, is effected by theengagement of idler wheels on the drive belts, which engagement occurson belts that transmit drive torque from the engine to the input to thetransmission instead of to the output of the transmission as has beenthe practice of the prior art. As a result, because the clutchingfunction is imposed on drive belts subjected to high speed but lowtorque, as contrasted with the converse, which prevails with prior artbelt driven machines of the concerned type, undue wear caused by beltslippage is avoided. Therefore, the frequency of belt replacement, withits attendant inoperability of the machine, is significantly reduced.

Undue stressing of drive belts utilized in the described machine isfurther reduced by the fact that the idler pulleys are caused to engagethe associated belts on the inside surface of the belts, i.e., the samesurface as is engaged by the driving and driven pulleys of the system.Thus, compressive stresses are continuously imposed upon the inside beltsurface while the outside belt surface is continuously stressed intension. These continuous stress conditions are contrasted with priorart devices wherein, due to the idler pulley engaging the concernedbelts on the side opposite that engaged by the drive and driven pulleys,the belts undergo the alternate imposition of compression and tensionstressing which results in increases in belt fatigue and rapid beltwear.

Drive Controls Kinematics

FIG. 18 shows a schematic of the right side of the controls in theneutral position. The left side is exactly the same. Note that thepivots 106, 126 and 133 on the drive lever 108 are not collinear.Further, the pivots 106 and 117 are fixed with respect to the mowerstructure while the pivots 126, 119 and 133 are movable with respect tothe mower structure as indicated by the arcuate broken lines in thefigure. Also, as indicated when FIG. 18 is considered conjunction withFIG. 4, the relative position of each of the pivots 117, 119, 133, 106,and 126 provide for a variable output to the idler pulley levers 92, 94with a constant input to the control handles 114, 116.

FIG. 19 graphically depicts the variable output to the input pulleylevers 92, 94 and the brake levers 134. The horizontal axis representsthe input to the control handles 114, 116. When one of the controlhandles 114, 116 is in the left portion of this chart, the respectivebrake band 138 is tightened against the brake drum 144. When one of thecontrol handles 114, 116 is in the right portion of the chart, therespective idler pulley arm 92 or 94 has the idler pulley 96 or 98attached thereto engaged with its associated belt 84 or 86.

Linear line 500 shows that the output to the arm 115 is at a constantratio with the input to either control handle 114, 116 since the arm 115is rigidly attached to the control handle 114 or 116. Lines 502, 504 and506 are non-linear. Line 502 represents the output of each of the drivelevers 108, 110.

Line 504 represents movement occurring to overcome the input to theidler pulley lever 92, 94. The horizontal portion of this linerepresents the lost motion coupling provided by the elongated loop 124.The slope of line 504 which represents the rate of movement of therespective control handles 114, 116 after overcoming lost motion isinitially large and decreases as the concerned control handle 114, 116is moved from the neutral position to the drive position. The smallslope of this line 504 over the final range or movement toward the driveposition allows for small input by the operator in order to get a fineadjustment of the tension on the drive belt 84, 86. This small inputdoes not require much effort by the operator. Furthermore, this is theregion of motion most used during the operation of the lawn mower. Theregion of this line 504 where the slope is large corresponds to theinitial movement of the idler pulley arm from its disengaged position toits engaged position. There is no resistance on the idler pulley arm inthis region since it has not yet fully engaged the drive belt 84, 86.Thus, there is little effort required by the operator.

Line 506 represents the input by the respective control handles 114 and116 to the brake lever 134. In the braking region of this chart, theslope increases as the concerned control handle 114, 116 is moved fromthe neutral position to the brake position. This translates into a smallbraking force during initial movement of the control handle 114, 116 anda large braking effort at the final brake position. The region of smallbraking effort encounters a small biasing force by the brake band 138 toreturn the control handle 114, 116 to the neutral position. Since thisis the most frequently used braking region during the operation of thelawn mower, the effort by the operator is also small.

It should be noted that the output lines 504 and 506 may be of any shapeas long as the slope of line 504 decreases from the neutral position tothe drive position and the slope of line 506 increases from the neutralpositon to the brake position.

Safety Cut-Off System

The safety cut-off system in accordance with the instant invention willbe described in connection with the figures set forth below.

FIGS. 1-4 illustrate the overall view of the mower including thearrangement of the handle bar controls. As illustrated in FIGS. 3-5,left forward presence lever 201 and right forward presence lever 202 aredisposed near left upper control handle 114a and right upper controlhandle 116a. Furthermore, the general elongated shape of left forwardpresence lever 201 and right forward presence lever 202 generallyfollows the elongated shape of upper left control handle 114a and upperright control handle 116a. Furthermore, as noted in FIGS. 3 and 4, thegeneral elongated shape of reverse presence lever 203 is similar to theelongated shape of the generally horizontal end portion 57 of handle bar56. As seen in FIG. 2, in profile, left forward presence lever 201,right forward presence lever 202 and reverse presence lever 203 aregenerally flat so that they may be easily be grasped together withanother bar. Left forward presence lever 201 is easily grasped togetherwith left upper control handle 114a, while right forward presence lever202 is conveniently grasped together with upper right control handle116a. Accordingly, reverse presence lever 203 is conveniently graspedtogether with horizontal end portion 57 of handle bar 56, in addition tolower control levers (or reverse control levers) 114b and 116b.

FIG. 13 is a partial perspective view isolating right forward presencelever 202 along with its corresponding upper right control handle 116aand lower right control handle 116b. Specifically, as noted, rightforward presence lever 202 generally follows the shape of upper rightcontrol handle 116a. Accordingly, wherever it is possible to grasp upperright control handle 116a, right forward presence lever 202 is alsoeasily grasped at the same time. Because the control handle 116 ispivotable with respect to handle bar 56 through a relative large angle,right forward presence lever 202 is pivotably mounted directly to theright control handle 116. In fact, since right forward presence lever202 pivots with respect to right control handle 116, it is always nearto upper right control handle 116a, no matter how little or how farupper right control handle 116a is pivoted. Normally open, right forwardsensor switch 208 is fixed with respect to right control handle 116.Furthermore, a switch arm 204 extends generally forwardly from rightforward presence lever 202 and is fixed with respect thereto. A spring206 is provided between right forward presence lever 202 and upper rightcontrol handle 116a, such that right forward presence lever 202 isbiased in the OFF state (disengaged state) and thus switch arm 204 isnot engaged with plunger 210. When right forward presence lever 202 isgrasped together with upper right control handle 116a, that is, theright forward presence lever 202 is now in the ON state (engaged state)switch arm 204 accordingly pivots and presses down plunger 210 of switch208. This action causes switch 208 (which is a normally open switch) tobe closed and thus to conduct electrical current between contacts 212,to which control wires are connected. The arrangement of the leftforward presence lever with respect to the left control handle 114 issubstantially a mirror image of the right forward presence lever 202 andright control handle 116, illustrated in FIG. 13. FIG. 2 illustratesleft forward presence lever switch 220 which is opposite the rightforward presence lever sensor switch 208.

FIG. 14 illustrates the relationship between the reverse presence lever203 and handle bar 56. Handle bar 56 is fixed with respect to the mower.Also, as seen in FIGS. 3 and 4, the generally horizontal end portion 57of handle bar 56 is generally parallel with reverse presence lever 203.Reverse presence lever 203 is pivoted with respect to handle bar 56.When reverse presence lever 203 is grasped together with horizontal endportion 57 of handle bar 56, reverse presence lever 203 is substantiallyadjacent horizontal end portion 57 of handle bar 56. A reverse presencelever switch arm 216 extends downwardly from reverse presence lever 203and is adaptable to engage plunger 222 of reverse presence lever sensorswitch 214. When reverse presence lever 203 is in the OFF state, it isbiased away from horizontal end portion 57 of handle bar 56 by spring218. Reverse presence lever sensor switch 214 is a normally open switch.Thus, when reverse presence lever 203 is in the OFF state (disengagedstate) reverse presence lever sensor switch 214 is maintained open. Whenthe reverse presence lever 203 is grasped together with horizontal endportion 57 of handle bar 56, switch arm 216 is pivoted to contactplunger 222 and accordingly to close sensor switch 220.

FIG. 15 is a schematic diagram of the control circuit layout forcontrolling the safety cut-off system in response to the operation ofthe presence levers and control levers. Reference numeral 240 generallyrefers to the circuit for controlling the safety cut-off system. Circuit240 is connected to connection block 236 with labeled connections B-F.Connection block 236 is in turn connected to switching module 238, whichis manufactured by Delta Systems, Inc. as Model No. 1201. Of course,module 238 may be any type of a switching module with relays, switches,electronic switches, a programmed logic array, or any other appropriateswitching device.

Engine magneto 234 is connected to key switch 230 and is also connectedto contact B. Key switch 230 is normally open when the engine isrunning. The opposite side of key switch 230 is connected to ground,thus when key switch 230 is closed, the engine magneto is grounded andthe mower is prevented from running. On the side of key switch 230,opposite the engine magneto, key switch 230 is also connected to contactE. An hour meter 232 is connected between contact points B and E.Contact point C is connected to a front side of reverse gear sensorswitch 226 (normally closed) and to the front side of reverse presencelever sensor switch 214. The back side of reverse gear sensor switch 226is connected to a first lead of left forward presence lever sensorswitch 220 and in parallel to a first lead of right forward presencelever sensor switch 208. The first lead of left forward presence leversensor 220 is also connected to a first lead of power take-off sensorswitch 228 (normally closed). The second lead of power take-off sensorswitch 228 is connected to contact D. The second lead of left forwardpresence lever sensor switch 220 is connected to contact F. The secondlead of right forward presence lever sensor switch 208 is connected to asecond lead of reverse presence lever sensor switch 214 and to contactF.

During operation, in its most basic sense, one or both of the forwardpresence levers 201, 202 are pushed forward (into the ON state) when thelawn mower is neutral or forward gear, and while pushing forward on theupper control handles 114, 116. When the lawn mower is in reverse gear,the reverse presence lever 203 is depressed onto the horizontal endportion 57 of handle bar 56, while pulling backward on lower controlhandles 114b, 116b. Module 238 functions to connect contact E (at groundpotential) to contact B to provide a ground level signal to the enginemagneto and thus prevent the motor from running. When contact C isconnected to contact D or F, then the connection between contact B andcontact E is broken, and thus contact B is no longer at groundpotential, therefore enabling the motor to run.

As noted, reverse gear sensor switch 226 is normally closed. This meansthat when reverse is gear engaged, switch 226 becomes open. When switch226 becomes open, the only way for contact C to conduct to contact F isthrough reverse presence lever sensor switch 214. In order words, theonly way to prevent cutting-off of the motor is to engage (put into theON state) the rear presence lever 203. Thus, if the gear shift is in thereverse gear, irrespective of the status of right forward presence leverswitch 208, left forward presence lever switch 220 and power take-offsensor switch 228, the reverse presence lever sensor switch 214 must beclosed in order to prevent a cut-off of the motor.

When the lawn mower is in neutral or a forward gear, reverse gear sensorswitch 226 is closed. Accordingly, any one of reverse presence leversensor switch 215, left forward sensor switch 220, or right forwardsensor switch 208 may be closed (either of the two forward presencelevers or the reverse presence levers in the ON state) in order toprevent contact B (and thus the engine magneto) from being grounded.

Power take-off lever sensor switch 228 is normally closed. That is, whenthe power take-off unit is engaged, the switch is open, and when thepower take-off unit is disengaged then switch 228 is closed.

A clear view of how the schematic diagram of FIG. 14 works can be seenwith reference to the following table A.

                  TABLE A                                                         ______________________________________                                                            Right  Left                                               No.   Gear   PTO    Fwd PL Fwd PL Rev PL  Engine                              ______________________________________                                        1     N-4    ON     OFF    OFF    OFF     OFF                                 2     N-4    ON     ON (OFF)                                                                             OFF (ON)                                                                             OFF (ON)                                                                              ON                                  3     N-4    OFF    OFF (ON)                                                                             OFF (ON)                                                                             OFF (ON)                                                                              ON                                  4     R      OFF    OFF    OFF    OFF     OFF                                 5     R      OFF    ON (OFF)                                                                             OFF (ON)                                                                             OFF     OFF                                 6     R      OFF    OFF (ON)                                                                             OFF (ON)                                                                             ON      ON                                  7     R      ON     OFF    OFF    OFF     OFF                                 8     R      ON     ON (OFF)                                                                             OFF (ON)                                                                             OFF     OFF                                 9     R      ON     OFF    OFF    ON      ON                                  ______________________________________                                    

As can be seen from Table A, the different status of the right forwardpresence lever, the left forward presence lever and the reverse presencelever affect the engine depending on which gear is selected and whetherthe power take-off unit (PTO) is engaged (ON) or disengaged

(OFF). Specifically, items 1-3 illustrate the situation in which thegear selector is in neutral or forward gears 1-4. In this situation, ifthe PTO is on, the engine will be prevented from running if neither theright forward presence lever 202, the left forward presence lever 201nor the reverse presence lever 203 are in the ON position. Item 2indicates that if one of the three presence levers is ON, then the motoror engine will not be prevented from running. Item 3 indicates that ifthe PTO is OFF and neutral or a forward gear is selected, then theposition of the presence lever does not matter and the engine is notprevented from running.

Items 4-9 indicate the situation in which the lawn mower is in reversegear. As can be seen in items 4-9, whether the PTO is ON or OFF, theonly condition which will allow the motor to be ON is when the reversepresence lever 203 is also in the ON state.

A presence lever guard 490 is attached to the handle bar 56 as shown inFIGS. 3-5. This guard 490 has a central plate 492 extending upwardlyfrom a center position on the horizontal end portion 57 of the handlebar 56. A top plate 494 extends generally forwardly from the top edge ofthe central plate 494 and substantially over a portion of said reversepresence lever 203.

The reverse presence lever 203 is free to move within the space definedby the horizontal end portion 57 and the presence lever guard 490.However, the presence lever guard prevents inadvertent operation of thereverse presence lever by the operator because the presence lever guardis positioned between the operator and the reverse presence lever.

Parking Brake

The disclosed mower includes a parking brake assembly identifiedgenerally by reference numeral 300 and described with particularreference to FIGS. 8, 10, 11 and 12 of the drawings. The parking brakeapparatus for the respective drive wheels 36 and 38, includes the drivelevers 108, 110, which operate to constrict the brake bands 138 aboutthe hubs of the respective drive wheels through activation of brakelevers 134 by the respective drive levers and connecting links 135 whichrigidly connect the brake levers to the drive levers.

The parking brake assembly 300 includes an operating shaft 302 whichextends laterally across the rear of the bed 16 of the power deck 12,with the opposite ends of the shaft being mounted for rotation inopenings 146 formed in the side flanges 20 of the bed plate 18. A pedalarm 304 having a foot pedal 306 attached at its free end is fixedlysecured to the operating shaft 302, whereby the operating shaft iscaused, when activated, to rotate in a counter-clockwise direction, asviewed from the right hand end in FIG. 11.

As shown in the drawing figures, each drive lever 108, 110 has a pawl308 in the form of an inclined U-shaped projection extending from a sidesurface of a depending leg of the drive lever. The operating shaft 302contains a pair of locking fingers 310 and 312, each of which containsan upwardly facing side edge 314 having an arcuately formed portionadjacent the free end and having locking teeth 316 thereon adapted toengage the pawls 308. In order to facilitate engagement of the pawls 308on the drive levers 108, 110 with the locking teeth 316 on the lockingfingers 310, 312, the free ends of the teeth are arcuately formed. Also,as shown in FIG. 12 which illustrates a drive lever 108, 110 in both ofits extreme positions of engagement with the locking levers, theinclination of the pawls 308 and the disposition of the teeth 316 alongthe locking finger edge 314 is such as to ensure a full surfaceengagement of the pawl with the teeth wherein the engagement forcevectors are substantially normal to the engaging surface on the pawl, asindicated by direction lines 318 and 320.

According to the invention, the locking finger 310 is fixed, as by meansof welding, to the operating shaft 302 so as to rotate with the shaft. Areturn spring 321, which is connected at one end to a hole 322 in thelocking finger 310 and whose other end is fixed with respect to the bed16, biases the locking finger 310, and consequently the shaft 302, in adirection away from the drive levers. This bias is overcome when thefoot pedal 306 is depressed.

Locking finger 312 is connected to the operating shaft 302 in a manneras to permit a restricted amount of relative movement with respect tothe shaft in order to provide a lost motion function between the lockingfinger and the shaft. As shown, the locking finger 312 has a clearancehole 324 through which the operating shaft 302 loosely passes. A pair ofradially extending pins 326 and 328 are fixed to the shaft at axiallyspaced locations therealong. Pin 326 is positioned closely adjacent theright side of locking finger 312, as viewed in FIG. 11, and pin 328 islocated at a position remote from the left side of the locking finger. Atorsion spring 330 surrounds the operating shaft 302 between the leftside of locking finger 312 and the radial pin 328. A tang 332 on theright end of the torsion spring 330 attaches the locking finger 312 viaa connecting hole 334 therein. The left end of the torsion spring 330contains an arm (not shown) which bears against radial pin 328. Duringassembly of the torsion spring onto the shaft, the spring is pre-loadedin a tightening direction so as to bias the movable locking finger 312upwardly toward the adjacent pawl 308, with such upward movement beinglimited by engagement of the tang 332 with the radial pin 326.

As is evident from consideration of FIG. 11, the locking fingers 310 and312 are not angularly aligned about the operating shaft 302. Instead,the movable finger 312 is displaced angularly upwardly with respect tothe fixed finger 310 so as to engage the pawl 308 on drive lever 108prior to engagement by the fixed finger 310 with the pawl 308 on drivelever 110. As a result of this construction, depression of the footpedal 306 by the machine operator causes, first, the teeth 316 on themovable locking finger 312 to engage the pawl 308 on the drive lever 108in order to lock the drive lever, and concomitantly, the associatedbrake lever 134 in their counter-clockwise positions to hold the brakeband 138 constricted about the brake drum 144 of the left drive wheel.Immediately, thereafter, the fixed locking finger 310 is brought intoengagement with the pawl 308 on drive lever 110 so as to secure thedrive lever in its braked condition, limited continued rotation of theoperating shaft 302 being permitted due to the lost motion functioneffected by the coupling of locking finger 312 to the operating shaft302 through the torsion spring 318.

The operation of the described parking brake assembly 300 is as follows.When the drive control handles 114 and 116 that connect with drivelevers 108 and 110, respectively, are pulled backward by the machineoperator, the brake bands 138 constrict brake pads 142 about the brakedrums 144 to apply a braking force to the respective drive wheels 36,38. The residual forces developed in the brake bands 138 bias thecontrol handles 114 and 116 to a neutral position on the handle bar 56,which position is intermediate their "drive" position and their "brake"position. Coincident with this, drive levers 108, 110 and theirassociated brake levers 134 tend to move in a counterclockwise directionas viewed in FIG. 10.

The parking brake function is initiated by the machine operatordepressing the foot pedal 306 with the wheel brakes being manuallyapplied and the control handles 114, 116 being held by the operator intheir "brake on" or rearward position. Consequently, operating shaft 302is rotated counter-clockwise to move the locking fingers 310, 312 towardthe pawls 308 on the respective drive levers 108, 110 whereupon lockingteeth 316 on the movable locking finger 312, which is upwardly biasedout of alignment with fixed locking finger 310, are caused to engage thepawl 308 on the drive lever 110. With the torsion spring 330 providing alost motion coupling between the movable locking finger 312 and theoperating shaft 302, the shaft continues to rotate until the lockingteeth 316 on the locking finger 310 engage the pawl 308 on drive lever110.

A force perpendicular to the end face of the pawl 308 results when theteeth 316 engage the pawl 308. This force is the result of theinclination of the pawl 308 and the bias on the drive lever 108, 110 torotate clockwise. The direction of this force is represented in FIG. 12by lines 318 and 320 for the two positions illustrated.

The force generated between the teeth 316 and the pawls 308 is directedover the pivot (i.e., the center of the operating shaft 302) of thelocking fingers 310 and 312. This force wants to rotate the lockingfingers 310 and 312 upwardly (counterclockwise). However, the pawls 308(which are attached to the drive levers 108 and 110) want to rotateclockwise to the "neutral" drive lever position of the drive levers 108and 110. Thus each engaged member has a force applied to it that biaseseach member further into engagement.

This perpendicular force creates a frictional force between the engagedtooth 316 and the pawl 308. This frictional force is perpendicular tothe force along line 318 or 320. This frictional force counteracts theforce of the return spring 321 attached to the locking finger 310. Theinteraction of the perpendicular force, the friction force and thereturn spring force creates a self-locking relationship between thepawls 308 and the locking fingers 310 and 312. Therefore, the parkingbrake assembly remains engaged.

For releasing the parking brake, the machine operator pulls the controlhandles 113, 116 rearwardly. Such action causes movement of the drivelevers 108, 110 in a clockwise direction which results in the pawls 308being removed from engagement with the locking teeth 316. When thisoccurs, the force resisting the return spring 321 is removed and thefixed locking finger 310 falls away from its associated pawl 308 therebymoving with it the operating shaft 302 and the movable locking finger312 whereupon the parking brake becomes fully disengaged.

From the foregoing, it is evident that the described parking brakeorganization is of simple, inexpensive construction, yet is effectivefor its intended purpose and, moreover, as compared with comparabledevices of the prior art, permits location of the parking actuator in anuncongested, easily accessible location on the mower.

It will be understood that various changes in the details, materials andarrangements of parts which have been herein described and illustratedin order to explain the nature of the invention, may be made by thoseskilled in the art within the principle and scope of the invention asexpressed in the appended claims.

Blade Brake Assembly

The blade brake assembly in accordance to the instant invention isoperated when the power take-off unit is disengaged. Specifically (asseen in FIG. 16), the power take-off unit includes a power take-off(PTO) drive pulley 88 driven by the motor, and PTO drive belt 90 drivenby the PTO drive pulley 88. Mower deck drive pulley 428 is engaged withPTO drive belt 90 and is driven by it. Mower deck drive pulley 428 isattached to and co-axial with shaft 430 which drives the center mowerblade. A mower deck drive belt 436 is threaded around center mower deckpulley 444, immediately beneath mower deck drive pulley 428 and alsosupported on shaft 430. The mower deck drive belt 436 is also threadedaround right side mower deck pulley 440, which is supported on shaft 434which also support the right side mower blade. The mower deck drive belt436 is furthermore threaded around left side mower deck pulley 442 whichis disposed immediately beneath the blade brake assembly 446 and issupported on left side shaft 432 which also supports the left side mowerblade. A mower deck tension pulley 438 provides proper tension on mowerdeck drive belt 436 for driving all three mower blades. PTO idler pulley414 is inserted in contact with PTO drive belt 90 between PTO drivepulley 88 and mower deck drive pulley 428. When PTO idler pulley 414 isengaged with PTO drive belt 90 and is biased outwardly, the powertake-off unit is engaged and the mower deck drive pulley 428 is driven.When PTO idler pulley 414 is shifted inwardly (as shown in phantom) sothat it no longer applies tension on PTO drive belt 90, the powertake-off unit is disengaged. In other words, mower deck drive pulley 428is not driven.

PTO idler pulley 414 is shifted inwardly to disengage the PTO unit. PTOidler pulley 414 is shifted inward in response to PTO control lever 402,as best seen in FIGS. 5 and 16. PTO control lever 402 is connected byway of upper rod 404 to first arm 406. First arm 406 is fixed withrespect to second arm 408 by way of collar 410. Collar 410 is supportedby and rotates around shaft 106. Second arm 408 is connected by way oflower rod 412 to a lower mounting fitting 427. Furthermore, a dampingspring 422 is provided on a remote end of lower rod 412, on the oppositeof lower mounting fitting 427 from second arm 408. An idler pivot 420fixed to the power deck includes first PTO idler arm 416 and second PTOidler arm 418. First PTO idler arm 416 extends outwardly from idlerpivot 420 and rotatably supports PTO idler pulley 414. Second PTO idlerarm 418 extends outwardly from idler pivot 420 and provides a mountingsurface for lower mounting fitting 427 which provides for a pivotalconnection with rod 412. An upper mounting fitting 426 is provided onthe upper portion of second PTO idler arm 418. In response to themovement of rod 412, second PTO idler arm 418, and in turn first PTOidler arm 416 pivots about idler pivot 420, thus causing PTO idlerpulley 414 to move inwardly (as shown in phantom) and outwardly withrespect to the PTO drive belt 90. Belt guide 424 is simply provided toprevent PTO drive belt 90 from slipping off of PTO idler pulley 414 asit releases its tension and moves inwardly with respect to the belt.Thus, when PTO idler pulley 414 is shifted inwardly, the PTO unit isdisengaged.

As illustrated in FIG. 2, the lawn mower having a blade braking systemin accordance with the instant invention is adjustable for differentcutting heights. Specifically, as seen in FIG. 2, the mower deck 14 isillustrated in its high position. It is also illustrated in its lowposition 15, as indicated in phantom. The lawn mower is supported on theground by drive wheels 36, 38 in the rear and by caster wheels 42, 44 inthe front. Support arms 40 are fixed with respect to the power deck 12.At the forward end of support arms 40, the caster wheels 42, 44 aresupported. A support shaft housing 460 is fixed to the forward end ofeach support arm 40, and supports a caster support shaft 458 therein.Support housing 460 is adjustable up and down along the length of castersupport shaft 458, in order to raise and lower support arms 40 withrespect to the caster wheel and the ground. Mower deck 14 is mounted tosupport arm 40 by way of a pair of brackets 448 (FIG. 16) which aresupported on support arm 40 by way of pivot pin 450 (FIG. 2) beinginserted in opening 451 of bracket 448 (FIG. 16). While the left side isbeing described, it should be noted that the right side is similar.

As illustrated in FIG. 16, a height adjusting mechanism is generallyindicated by the arrow 452 and includes a pivot bar 454 which pivots(through angle 453) with respect to support arms 40 and has an inwardlyextending engaging end 455. The engaging end 455 supports bracket 456which is fixed to the top of the lawn mower deck. As pivot bar 54 pivotsor rotates (through angle 453) with respect to support arm 40, theinwardly engaging ends 455 shifts downward with respect to support arm40. Since engaging ends 455 support brackets 456 and thus mower deck 14,as engaging ends 455 shift downwardly, so do brackets 456 andaccordingly mower deck 14. However, mower deck 14 is pivoted at pivotpin 450 (FIG. 2). Thus, the mower deck pivots downwardly and does notremain level with respect to the ground. This causes two concerns. Thefirst concern is maintaining the mower deck and the mower blade in aposition substantially parallel to the ground. This is accomplished byadjusting the height of support shaft housing 460 with respect to castersupport 458. Therefore, when the mower deck 14 is adjusting downwardlyor upwardly by the height adjusting mechanism 452, the support shafthousings 460 are also adjusted to compensate.

A second concern arising from the pivoting deck is the proper connectionof a linkage to the blade brake for braking the mower blades when thePTO unit is disengaged. This solution will be described below.

When the PTO is disengaged, then ANSI regulations require the blades tostop moving within specified amount of time. Thus the blade brake shouldbe applied when the lawn mower is shifted into the PTO disengaged state.Accordingly, as illustrated in FIG. 16, actuating rod 462 is connectedto second PTO idler arm 418 by way of pivotable upper mounting fitting426. Actuating rod 462 extends forwardly from second PTO idler arm 418to pivot lever 464. Pivot lever 464 pivots about a center pivot 466which is fixed to mower deck 14 (illustrated as 14' in FIG. 17). Pivotlever 464 (as seen in FIGS. 16 and 17) transfers the longitudinalreciprocating movement of actuating rod 462 indicated by arrow a intothe longitudinal reciprocating movement of link member 468 indicated byarrow b. Center pivot 466 and pivot lever 464 are fixed to the mowerdeck at a point near the mower deck pivot pin 450 which pivots inopenings 451 of brackets 448. As noted in FIG. 17, the forward end ofactuating rod 462 has a connecting end 476 extending generallyperpendicular to the actuating rod 462. Connecting end 476 is insertedinto an oversize hole 478 such that actuating rod 462 is pivotable intwo different angular directions with respect to pivot lever 464.Actuating rod 462 pivots in a direction generally parallel to the planeof the pivot lever 462 as indicated by arrow c. Furthermore, because ofthe oversize hole 478 and the connecting end 476 of actuating rod 462,actuating rod 462 is also pivotable in a direction not parallel to theplane of pivot lever 464. In fact, actuating rod 462 is pivotable in adirection generally perpendicular to the plane of pivot lever 464 asindicated by arrow f. Link member 468 extends from a pivotal connectionwith a second end 474 of pivot lever 464 to connect with band brake 446.A support ring 470 (FIG. 16) is fixed to the mower deck to support anend of link member 468 nearest the band brake. As link member 468 shiftstoward the band brake, the band brake is applied, braking the left mowerblade and the other mower blades by way of mower deck drive belt 436. Asillustrated in FIG. 17, it is preferable that the distance between thecenter pivot 466 and the connection of pivot lever 464 with actuatingrod 462 indicated by d2 is greater than the distance from center pivot466 to the connection between pivot lever 464 and link member 468(indicated by d1). Since the pivot lever 464 is located near pivot pin450 of the mower deck, the pivotability of actuating rod 462 in twodifferent angular directions compensates for the pivoting of the mowerdeck when raising and lowering the height adjustment. Furthermore,because actuating rod 462 is a long rod and pivoted at pivot lever 464,any large change in lateral movement of actuating rod 462 at the endnearest the power deck is reduced to a smaller amount near pivot lever464. Furthermore, when d2 is greater than d1, any difference inlongitudinal motion of actuating rod 462 (between high and low cuttinglevels) is accordingly reduced in the longitudinal motion of link member468. Thus, the pivoting movement of the mower deck when changing cuttingheight is compensated for without requiring continued adjustment of theblade brake itself, and thus enabling the blade brake to always be inproper alignment, since it is fixed with respect to the location ofcenter pivot 466 and pivot lever 464.

In operation, when the operator moves the PTO control lever 402 toselect a disengaged state for the PTO unit, motion is transmittedthrough upper rod 404, first arm 406, collar 410, second arm 408, lowerrod 412, through lower mounting fitting 427 to pivot second PTO idlerarm 418 about idler pivot 420. When idler pivot 420 pivots in theclockwise direction, first idler arm 416 and PTO idler pulley 414,rotatably attached thereto, are pivoted in turn. As PTO idler pulley 414is shifted inwardly, the tension on PTO drive belt 90 is removed andpower to mower deck drive pulley 428 is removed. As second PTO idler arm418 moves forwardly, so does actuating rod 462, because it is pivotallyconnected to second PTO idler arm by way of pivotable upper mountingfitting 426. As actuating rod 462 moves forward, pivot lever 464 pivotsabout center pivot 466 and causes link member 468 to be movedlongitudinally toward blade brake assembly 446 and thus apply bladebrake assembly 446 to thereby stop the rotation of the mower blades.

When the PTO control lever 402 is returned to the engaged state toengage the PTO unit, each of the above elements operates in the reverseway to release band brake 446 and to allow the mower blades to spinfreely.

Ballast System

The ballast system in accordance with the instant invention can best beseen with reference to FIGS. 2-5. Ballast tank 252 is illustrated inthese figures. The ballast system in accordance with the instantinvention is used with a lawn mower 10 having a power deck 12 and amowing deck 14. An engine or motor 26 is positioned on bed 16 of powerdeck 12 for driving left and right drive wheels 36, 38. Mower deck 14 isattached to and extends forwardly from power deck 12 and is supported atits front end by caster wheels 42, 44. A fuel tank 34 is supported onbracket 32 located at the rear portion of power deck 12. Depending arms58, 60 extend upwardly and rearwardly from the power deck and are fixedto and supported by bracket 32. Ballast tank 252 is supported betweendepending arms 58, 60 of the handle bar 56. As seen most clearly inFIGS. 2 and 3, ballast tank 252 is disposed near the end of handle bar56, remote from power deck 12. FIGS. 2 and 3 illustrate a filler cap 254or opening the top of ballast tank 252 to fill the interior volume withthe desired ballast, whether water, sand or any other appropriateballast. Draining cap 256 allows the ballast to be easily drained outfrom ballast tank 252.

As clearly seen in FIG. 2, ballast tank 252, disposed near an end ofhandle bar 56, is located behind the center line of drive wheels 36, 38.In fact, the ballast tank 252 is disposed behind the rearmost portion ofdrive wheels 36, 38. Furthermore, it should be noted that ballast tank252 is disposed at least partially behind fuel tank 34.

In operation, the filler cap 254 may simply be removed by the operatorand ballast tank 252 may be filled with water, sand or any otherappropriate ballast. Cap 254 may then be replaced. The appropriateballast in ballast tank 252 will change the center of gravity of thelawn mower itself. It will aid to counter balance the mower deck 14attached on the front of the power deck 12. This will aid in handlingthe lawn mower in tight places, or under any other circumstances.Because ballast tank 252 is disposed high up on handle bar 56, in orderwords, near the end of handle bar 56, this arrangement increases themovement arm of any ballast in ballast tank 252, thus increasing theefficiency of any such ballast. When finished, the user may drain theballast through drain cap 256.

It should also be noted that although the above description has been setforth with regard to the mower deck 14, the power deck 12 may also beemployed with a snow blower, auxiliary unit, a power sweeper auxiliaryunit or many other types of auxiliary units. As an example, the lawnmower deck may have a different weight than the snow blower auxiliaryunit or the power sweeper auxiliary unit. Accordingly, because theballast tank 252 has an interior volume that may accept varying amountsof ballast, the ballast tank 252 may be filled full, or may be partiallyfilled to compensate for different weights of the different auxiliaryunits, such as the mower deck, the snow blower auxiliary unit and thepower sweeper auxiliary unit.

Although a specific form of embodiment of the instant invention has beendescribed above and illustrated in the accompanying drawings in order tobe more clearly understood, the above description is made by way ofexample and not as a limitation to the scope of the instant invention.It is contemplated that various modifications apparent to one ofordinary skill in the art could be made without departing from the scopeof the invention which is to be determined by the following claims.

What is claimed is:
 1. A self-propelled, walk-behind power toolcomprising:a power deck including a bed, an engine mounted on an uppersurface of said bed and having a rotatable drive shaft dependingtherethrough, left and right drive wheels each being journalled onopposite sides of said bed for rotation about an axle, and means forconnecting said engine to said drive wheels including a pair of idlerpulley levers pivotally attached to said bed, a handle bar attached to arear side of said power deck, left and right control handles operativeto control operation of said left and right drive wheels, respectively,positioned on said handle bar, means for biasing each of said controlhandles to a neutral position, said control handles being pivotable fromsaid neutral position to a drive position, and first means for movingeach of said idler pulley levers at a first rate in response to aconstant input to pivot each control handle from said neutral positionto a first position intermediate said neutral and drive positions, andat a second rate in response to said constant input to pivot eachcontrol handle from said intermediate position to said drive position.2. A self-propelled, walk-behind power tool according to claim 1 furthercomprising:a pair of brake levers attached each to one of said drivewheels and being pivotally attached to said bed, said biasing meansbiasing said control handles from a brake position opposite said driveposition to said neutral position, and second means for moving each ofsaid brake levers at a first rate in response to a constant input topivot said control handle from said neutral position to a secondposition intermediate said neutral and brake positions, and at a secondrate in response to said constant input to pivot said control handlefrom said second position to said brake position.
 3. The power tool ofclaim 1 wherein said first rate of movement of said idler pulley leversis greater than said second rate.
 4. The power tool of claim 3 whereinthe transition from said first rate to said second rate is smoothlycontinuous.
 5. The power tool of claim 1 wherein said means for movingeach said idler pulley lever comprises a drive lever having an end pivotlocated at each of its upper and lower ends and a central pivot betweensaid end pivots, said central pivot being fixed while said end pivotsare movable, the distance from said lower end pivot to said centralpivot is greater than the distance from said upper end pivot to saidcentral pivot, and said drive lever pivots are not collinear.
 6. Thepower tool of claim 5 wherein said pivots in each of said drive leversdefine an obtuse angle with respect to each other.
 7. The power tool ofclaim 5 wherein said means for moving each said idler pulley leverfurther comprises an arm, said arm having a fixed pivot and a movingpivot, an axis connecting said pivots of said arm being inclined fromhorizontal at an angle that is smaller than an axis connecting saidupper end pivot and said central pivot of said drive lever in saidneutral position, said pivots of said arm associated with the respectivedrive wheels being misaligned relative to said pivots for the drivelever of the concerned drive wheel in both the horizontal and verticaldirections, and the distance between said arm pivots being less than thedistance from said lower end pivot to said central pivot.
 8. The powertool of claim 2 wherein said first rate of movement of said brake levermoving means is less than said second rate of movement of said brakelever moving means.
 9. The power tool of claim 8 wherein said brakelever moving means has a smoothly continuous transition from said firstrate to said second rate.
 10. The power tool of claim 2 wherein saidmeans for moving said brake lever comprises a drive lever having a pivotlocated at each of its upper and lower ends and a central pivot betweensaid end pivots, said central pivot being fixed while said end pivotsare movable.
 11. The power tool of claim 10 wherein said means formoving said brake lever further comprises an arm, said arm having afixed pivot and a moving pivot, an axis connecting said pivots of saidarm being inclined from horizontal at an angle that is smaller than anaxis connecting said upper end pivot and said central pivot in saidneutral position, said pivots of said arm being misaligned relative tosaid pivots for said drive lever in both the horizontal and verticaldirections.
 12. The power tool of claim 11 wherein said brake lever hasa fixed pivot and a moving pivot, said pivots of said arm beingmisaligned relative to said pivots for said brake lever in both thehorizontal and vertical directions, an axis connecting said brake leverpivots being inclined from horizontal at an angle that is greater thanthe inclination of an axis connecting said upper end pivot and saidcentral pivot in said neutral position, said brake lever pivots beingmisaligned relative to said pivots for said drive lever in both thehorizontal and vertical directions, the distance between said brakelever pivots being longer than the distance from said upper end pivot tosaid central pivot.
 13. The power tool of claim 2 wherein said means formoving said idler pulley lever comprises a drive lever and an arm,saiddrive lever having an end pivot located at each of its upper and lowerends and a central pivot between said end pivots, said central pivotbeing fixed while said end pivots are movable, the distance from saidlower end pivot to said central pivot being greater than the distancefrom said upper end pivot to said central pivot, said drive lever pivotsdefining an obtuse angle, said arm having a fixed pivot and a movingpivot, an axis connecting said pivots of said arm being inclined from ahorizontal at an angle that is smaller than an axis connecting saidupper end pivot and said central pivot of said drive lever in saidneutral position, said pivots of said arm being misaligned relative tosaid pivots of said drive lever in both the horizontal and verticaldirections, and the distance between said arm pivots being less than thedistance from said lower end pivot to said central pivot thereof. 14.The power tool of claim 13 wherein said means for moving said brakelever comprises said means for moving said idler pulley lever and aconnecting link connecting said brake lever at its moving pivot to saidupper end pivot of said drive lever.